BRUTE FORCE CHANNEL DECODING
First Claim
1. A method of decoding a received coded bit sequence, comprising:
- obtaining a plurality of codewords which said coded bit sequence may possibly represent;
for substantially each of the plurality of codewords, calculating a similarity measure with the received coded bit sequence to determine one of the codewords which most closely matches the coded bit sequence;
identifying an input bit sequence which, when encoded in the same manner as the received coded bit sequence, produces said determined codeword; and
outputting said identified input bit sequence to represent the decoded received coded bit sequence.
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Accused Products
Abstract
An embodiment of the present invention provides that pre-calculated code words corresponding to possible input bit sequences are stored in a UE, and then a similarity matching operation performed between a received coded bit sequence and the stored code words can be performed to identify that code word which most closely matches to the received sequence. Because the stored code words are associated with the original input bit sequences which produced those code words, by identifying the most closely correlating code word to a received coded sequence, then the input sequence which generated the matching code word can also be identified, and output as the decoder output. In this way, a more efficient decoding operation is obtained as decoding is no longer dependent upon a Viterbi decoding operation and moreover it is no longer necessary to implement a Viterbi decoder, instead merely requiring storage for the pre-calculated code words. In the specific case of the HS-SCCH Part 1 a code word table comprising 256 40 bit is required. This is significantly easier to implement and is more efficient in terms of chip area, than providing a dedicated Viterbi decoder to decode the HS-SCCH Part 1 channel.
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Citations
22 Claims
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1. A method of decoding a received coded bit sequence, comprising:
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obtaining a plurality of codewords which said coded bit sequence may possibly represent; for substantially each of the plurality of codewords, calculating a similarity measure with the received coded bit sequence to determine one of the codewords which most closely matches the coded bit sequence; identifying an input bit sequence which, when encoded in the same manner as the received coded bit sequence, produces said determined codeword; and outputting said identified input bit sequence to represent the decoded received coded bit sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 18)
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10. An apparatus comprising a decoder, the decoder comprising:
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i) a simililarity measurement calculator configured in use to calculate a similarity measure for substantially each of a plurality of codewords which said received coded bit sequence may possibly represent so as to determine one of the plurality of codewords which most closely matches the received coded bit sequence; ii) a bit sequence identifier configured in use to identify an input bit sequence which, when encoded in the same manner as the received coded bit sequence produces said determined codeword; and iii) an output at which said identified input bit sequence is output so as to represent the decoded received coded bit sequence. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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19-20. -20. (canceled)
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21. An apparatus comprising:
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a receiver arranged to receive in use data from a High Speed Shared Control Channel (HS-SCCH) corresponding to a High Speed Downlink Packet Access (HSDPA) downlink, the HS-SCCH data being configured in at least two parts, being a first part and a second part, each part being separately convolutionally encoded from the other part; and a first decoder arranged to decode the first part of the HS-SCCH data, the decoder comprising; a store storing possible codeword values of the first part of the HS-SCCH and associated unencoded values; and a similarity matching unit arranged in use to compare a received encoded first part data word with the stored codeword values to decode the received encoded first part data word whereby to identify the corresponding unencoded value. - View Dependent Claims (22)
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Specification